By using your "Complete Do-It-Yourself Package for EB1-OR", my I-140
application was approved about 8 months ago.
Now, my I-485 application is pending more than 180 days, and due to the current
economy and my company downsize, I may need to change employer, do I have to
notify the "Bureau
of Citizenship and Immigration Services" for my job changing?

Answer:

It is always better to let the USCIS know your job
change, even it is more than
180 days of I-485 pending. In this way, you will avoid the problem when
USCIS ask for the employment evidence for your I-485 approval. Also
it will avoid the fraud
investigation later when you apply for U.S. citizenship.